Romanovsky, Vladimir

Abstract [en]

This study describes detailed partitioning of phytomass carbon (C) and soil organiccarbon (SOC) for four study areas in discontinuous permafrost terrain, Northeast EuropeanRussia. The mean aboveground phytomass C storage is 0.7 kg C m−2. Estimated landscapeSOC storage in the four areas varies between 34.5 and 47.0 kg C m−2 with LCC (landcover classification) upscaling and 32.5–49.0 kg C m−2 with soil map upscaling. A nestedupscaling approach using a Landsat thematic mapper land cover classification for thesurrounding region provides estimates within 5 ± 5% of the local high‐resolutionestimates. Permafrost peat plateaus hold the majority of total and frozen SOC, especially inthe more southern study areas. Burying of SOC through cryoturbation of O‐ or A‐horizonscontributes between 1% and 16% (mean 5%) of total landscape SOC. The effect ofactive layer deepening and thermokarst expansion on SOC remobilization is modeled forone of the four areas. The active layer thickness dynamics from 1980 to 2099 is modeledusing a transient spatially distributed permafrost model and lateral expansion of peatplateau thermokarst lakes is simulated using geographic information system analyses.Active layer deepening is expected to increase the proportion of SOC affected by seasonalthawing from 29% to 58%. A lateral expansion of 30 m would increase the amount ofSOC stored in thermokarst lakes/fens from 2% to 22% of all SOC. By the end of thiscentury, active layer deepening will likely affect more SOC than thermokarst expansion,but the SOC stores vulnerable to thermokarst are less decomposed.